Conventionally, in an apparatus for changing the direction of conveying paper by 90 degrees, the paper is made to register or to abut against a metal plate stopper or the like. The paper is then pulled to a lower guide plate, while a transverse conveying force is exerted to the paper to send the paper out of the lower guide plate. Generally, with the conventional machine, a paper conveying system constitutes a combination of a belt and a ball to give the paper freedom rightward and leftward so that the paper can be moved in a transverse direction.
Difficulties have been encountered in the art as a result of the inability of the conventional apparatus to control paper of varying thickness. More precisely, if the conveying direction of a thin sheet of paper and paper folded several times is to be changed by 90 degrees by the above-mentioned apparatus, the thin sheet is deformed by the strong force necesary for conveying a thick folded sheet on one hand, while the thin sheet conveying force is insufficient for conveying a thick sheet. Thus, it is exceedingly difficult to determine the appropriate force for the paper being conveyed.